Non-breeding
plumage, with the breeding all-black head replaced by mostly white with
a lateral black streak at the back of the crown. The gray smudging
behind the dark streak suggests that this may be second-year rather
than the very similar adult non-breeding plumage.

Juvenile
Sabine's Gulls in September. Above, one that strayed into San Francisco
Bay and spent some time in the ponds of the Sunnyvale Water Pollution
Control Plant; below, a more normal sighting, flying
in the Pacific Ocean near the Farallon Islands.